"Elysium Fossa" wrote in message ...
A New Scientist atricle states that even if it develops into a global dust
storm it shouldn't affect the entry and landing, but could affect the
longevity of the mission.

http://www.newscientist.com/news/news.jsp?id=ns99994490


================================================== ========================
From: Robert Clark )
Subject: Could global dust storms allow open water pools on Mars?
Newsgroups: sci.astro, alt.sci.planetary, sci.geo.geology,
sci.geo.meteorology, sci.astro.amateur
Date: 2001-08-08 13:55:17 PST


(Paul Morris) wrote in message ...
Another interesting point, which I read elsewhere, is that during the dust storm
the day/night fluctuation in temperature can be as small as 10 degrees C. Note
that for pressures at certain locations on Mars, the liquid phase of water
extends
from 0 to 10 Celsius.

Paul




A very good point. As seen on this page the daily temperature
variations decrease markedly during the global dust storms:

Mars
Temperature overview
http://www-k12.atmos.washington.edu/..._overview.html

The last figure on this page shows the daily temperature variations
during a global 1977 dust storm at the Viking sites. I estimate from
this figure the smallest diurnal temperature variation as about 10° C
at VL 1 and about 5° C at VL 2.
The dust storms on this page are described as increasing the pressure
but decreasing temperatu

"Atmospheric dust causes daily pressure variations, proportional to
the dust amount; the magnitude of the daily variation can increase
rapidly, but decreases slowly as the dust falls out of the atmosphere
if its a deep, great dust storm. "Great" dust storms, such as the 1977
A and 1977 B storm, produce large increases in the daily pressure and
decreases in atmospheric temperature variations, which then slowly
recover over many tens of sols. During these dust storms, the maximum
daytime temperature decreases and the minimum, nighttime temperature
increases: the effect is very similar to that of clouds on Earth and
details will be presented in future enhancements. The effect of the
Martian dust storms provided some of the impetus for the study of the
"Nuclear Winter" concept in the TTAPS paper, authored by Turco, Toon,
Ackerman, Pollack and Sagan: the latter two were Viking Science Team
members."

The greatest pressure on Mars was observed around global dust storms
as shown in the first figure he

Mars
Instrument Testing Mission Operations Meteorological Data
http://www.atmos.washington.edu/loca...teorology.html

The average daily temperature during a storm is decreased by about
14° C:

The Viking Mission to Mars
3.4 Science
"Major atmospheric, and over long time scales, geological, process are
the global dust storms which decrease the daily average [surface]
temperature on the order of 14 degrees Celsius or approximately 25
degrees Fahrenheit. As the dust remains in the atmosphere for many
tens of sols, the effect was thought to be similar to that discussed
in Nuclear Winter: Global Consequences of Multiple Nuclear Explosions,
R.P. Turco, O.B. Toon, T.P. Ackerman, J.B. Pollack and Carl Sagan,
Science, 23 Dec. 1983, pp 1283-1292."
http://www.atmos.washington.edu/loca...y_npug_84.html

The temperatures at the Viking sites during the storms were quite low
since they occurred during local winter. However, note that at the
equator the temperature can reach around 27° C during the day. If
there is also a 14° C decrease here then the temperatures still might
be around 13° C. If the daily temperature variation was only 10° C as
at VL 1 then that would mean during the entire day the temperature
would remain above 0° C. However, note that comparing the VL 1
temperature variation with that at VL 2 the variation is greater at
higher temperatures, so you would expect the variation at the equator
to be higher than at the VL 1. However there may be intermediate
latitudes where the temperature would be above 0 during the entire
day.
An additional factor is that as the dust settles some of the dust
would settle on the south polar cap which might cause the entire cap
to melt increasing the pressure even further:

From: Robert Clark )
Subject: Could global dust storms melt the southern polar ice cap on
Mars?
Newsgroups: sci.astro, sci.astro.amateur, alt.sci.planetary,
alt.astronomy, sci.geo.meteorology
Date: 2001-07-20 11:36:46 PST
http://groups.google.com/groups?th=eb7f73c9108af924

Near equatorial areas where the temperature and pressure might be in
the liquid water range during the entire day include the lowest
elevation regions in Valles Marineris. A key question is whether there
would be water in the near equator latitudes. Recent research suggests
that there is:

From: Robert Clark )
Subject: UA Scientists Find Evidence For Geologically Recent
Shallow Ground Ice At Mars' Equator
Newsgroups: sci.astro, alt.sci.planetary, alt.astronomy,
sci.geo.geology
Date: 2001-06-14 06:14:36 PST
http://groups.google.com/groups?th=3...7bad70&start=1

Also observation of rock glacier like landforms suggests there may be
near surface ice in Valles Marineris currently:

Rock Glacier-like Landforms in Valles Marineris, Mars
http://adsabs.harvard.edu/cgi-bin/bi...PI....31.1587R

Also the suitable temperature range might extend outside the
equatorial region, such as to the Hellas basin for example. Gil Levin
has argued that during the local summer above freezing temperatures
were reached at the Viking lander sites actually on the surface at 48°
C latitude. His point was that temperatures increase as you approach
the surface during the daytime and should therefore be higher than the
temperatures measured on the Viking meteorology mast 1.5 meters above
the surface. Measurement of temperatures actually on the surface he
argues show the melting point of water being reached:

"Surface materials of the Viking landing sites", by Henry Moore
et.al.,
Journal of Geophysical Research, vol.82, no.28, Sept. 30, 1977, p.
4497-4523:

"It is noteworthy that the collector head temperature of VL-2 reached
273 degrees K or very close to the temperature of the triple point
of water. Since surface pressures are substantially greater than
6 mbar [Seiff and Kirk, 1976], it is entirely possible that pressure-
temperature conditions at the upper surface of Mars are in the
stability field of liquid water for short periods of time and in local
areas. This suggests that near-surface freeze-thaw cycles may exist.
Perhaps more data on surface temperatures using the collector head
temperature sensor can be obtained during the extended mission."
Surface materials of the Viking landing sites, p. 4522.

Further simulations of the Pathfinder site also show temperatures
above freezing being reached actually on the surface.


Bob Clark

================================================== ====================

Robert Clark wrote:

"Elysium Fossa" wrote in message ...
A New Scientist atricle states that even if it develops into a global dust
storm it shouldn't affect the entry and landing, but could affect the
longevity of the mission.

http://www.newscientist.com/news/news.jsp?id=ns99994490

================================================== ========================
From: Robert Clark )
Subject: Could global dust storms allow open water pools on Mars?
Newsgroups: sci.astro, alt.sci.planetary, sci.geo.geology,
sci.geo.meteorology, sci.astro.amateur
Date: 2001-08-08 13:55:17 PST


(Paul Morris) wrote in message ...
Another interesting point, which I read elsewhere, is that during the dust storm
the day/night fluctuation in temperature can be as small as 10 degrees C. Note
that for pressures at certain locations on Mars, the liquid phase of water
extends
from 0 to 10 Celsius.

Paul



A very good point. As seen on this page the daily temperature
variations decrease markedly during the global dust storms:

Mars
Temperature overview
http://www-k12.atmos.washington.edu/..._overview.html

The last figure on this page shows the daily temperature variations
during a global 1977 dust storm at the Viking sites. I estimate from
this figure the smallest diurnal temperature variation as about 10° C
at VL 1 and about 5° C at VL 2.
The dust storms on this page are described as increasing the pressure
but decreasing temperatu

"Atmospheric dust causes daily pressure variations, proportional to
the dust amount; the magnitude of the daily variation can increase
rapidly, but decreases slowly as the dust falls out of the atmosphere
if its a deep, great dust storm. "Great" dust storms, such as the 1977
A and 1977 B storm, produce large increases in the daily pressure and
decreases in atmospheric temperature variations, which then slowly
recover over many tens of sols. During these dust storms, the maximum
daytime temperature decreases and the minimum, nighttime temperature
increases: the effect is very similar to that of clouds on Earth and
details will be presented in future enhancements. The effect of the
Martian dust storms provided some of the impetus for the study of the
"Nuclear Winter" concept in the TTAPS paper, authored by Turco, Toon,
Ackerman, Pollack and Sagan: the latter two were Viking Science Team
members."

The greatest pressure on Mars was observed around global dust storms
as shown in the first figure he

Mars
Instrument Testing Mission Operations Meteorological Data
http://www.atmos.washington.edu/loca...teorology.html

The average daily temperature during a storm is decreased by about
14° C:

The Viking Mission to Mars
3.4 Science
"Major atmospheric, and over long time scales, geological, process are
the global dust storms which decrease the daily average [surface]
temperature on the order of 14 degrees Celsius or approximately 25
degrees Fahrenheit. As the dust remains in the atmosphere for many
tens of sols, the effect was thought to be similar to that discussed
in Nuclear Winter: Global Consequences of Multiple Nuclear Explosions,
R.P. Turco, O.B. Toon, T.P. Ackerman, J.B. Pollack and Carl Sagan,
Science, 23 Dec. 1983, pp 1283-1292."
http://www.atmos.washington.edu/loca...y_npug_84.html

The temperatures at the Viking sites during the storms were quite low
since they occurred during local winter. However, note that at the
equator the temperature can reach around 27° C during the day. If
there is also a 14° C decrease here then the temperatures still might
be around 13° C. If the daily temperature variation was only 10° C as
at VL 1 then that would mean during the entire day the temperature
would remain above 0° C.

No. It is stated that during a dust storm the daily average Temperature
is 14°C lower than without a dust storm. The daily average temperature
on Mars is everwhere below 0°C during als Seasons.
Even if the ground gets as warm as 27°C in the Afternoon it will go down
below -40°C during the night ...



However, note that comparing the VL 1
temperature variation with that at VL 2 the variation is greater at
higher temperatures, so you would expect the variation at the equator
to be higher than at the VL 1. However there may be intermediate
latitudes where the temperature would be above 0 during the entire
day.



An additional factor is that as the dust settles some of the dust
would settle on the south polar cap which might cause the entire cap
to melt increasing the pressure even further:

From: Robert Clark )
Subject: Could global dust storms melt the southern polar ice cap on
Mars?
Newsgroups: sci.astro, sci.astro.amateur, alt.sci.planetary,
alt.astronomy, sci.geo.meteorology
Date: 2001-07-20 11:36:46 PST
http://groups.google.com/groups?th=eb7f73c9108af924

Near equatorial areas where the temperature and pressure might be in
the liquid water range during the entire day include the lowest
elevation regions in Valles Marineris. A key question is whether there
would be water in the near equator latitudes.

Doubtful, the warmest places on Mars are on the southern hemisphere,
and there is at the moment no place where it is
above freezing through the whole day.
But during the last million years, when inclination of mars axis was
higher there may have been such places near the pole in summer.


Recent research suggests
that there is:

From: Robert Clark )
Subject: UA Scientists Find Evidence For Geologically Recent
Shallow Ground Ice At Mars' Equator
Newsgroups: sci.astro, alt.sci.planetary, alt.astronomy,
sci.geo.geology
Date: 2001-06-14 06:14:36 PST
http://groups.google.com/groups?th=3...7bad70&start=1

Also observation of rock glacier like landforms suggests there may be
near surface ice in Valles Marineris currently:

Rock Glacier-like Landforms in Valles Marineris, Mars
http://adsabs.harvard.edu/cgi-bin/bi...PI....31.1587R

Also the suitable temperature range might extend outside the
equatorial region, such as to the Hellas basin for example. Gil Levin
has argued that during the local summer above freezing temperatures
were reached at the Viking lander sites actually on the surface at 48°
C latitude. His point was that temperatures increase as you approach
the surface during the daytime and should therefore be higher than the
temperatures measured on the Viking meteorology mast 1.5 meters above
the surface.

Viking landed on the northern hemisphere. The northern summer on
Mars is about 30°C colder than the southern summer.
We have southern Summer now, look at the temperatures:
http://emma.la.asu.edu/webdata/daily_temp.gif


Measurement of temperatures actually on the surface he
argues show the melting point of water being reached:

"Surface materials of the Viking landing sites", by Henry Moore
et.al.,
Journal of Geophysical Research, vol.82, no.28, Sept. 30, 1977, p.
4497-4523:

"It is noteworthy that the collector head temperature of VL-2 reached
273 degrees K or very close to the temperature of the triple point
of water. Since surface pressures are substantially greater than
6 mbar [Seiff and Kirk, 1976], it is entirely possible that pressure-
temperature conditions at the upper surface of Mars are in the
stability field of liquid water for short periods of time and in local
areas. This suggests that near-surface freeze-thaw cycles may exist.
Perhaps more data on surface temperatures using the collector head
temperature sensor can be obtained during the extended mission."
Surface materials of the Viking landing sites, p. 4522.

Further simulations of the Pathfinder site also show temperatures
above freezing being reached actually on the surface.

Same problen - for Mars being really warm it must be southern
Summer, and the Site must be between 10° and 60° on the southern
hemisphere.